5.1. Integration with SBI MPXY Extension

A platform with a limited number of RPMI transport instances can share an M-mode RPMI transport instance with the supervisor software using the SBI MPXY extension [1]. An M-mode firmware or hypervisor can also virtualize RPMI message communication for the supervisor software using the SBI MPXY extension. As shown in the Figure 1 below, the SBI implementation acts as a RPMI proxy for the supervisor software when sending RPMI messages through an SBI MPXY channel.

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Figure 1. RPMI and SBI MPXY Integration

The RPMI communication via the SBI MPXY extension must satisfy the following requirements:

  1. The SBI MPXY channel must correspond to a single RPMI service group which is allowed in S-mode except BASE and CPPC service groups. The [table_service_groups] list the RPMI service groups allowed in S-mode.

  2. The SBI MPXY channel corresponding to the RPMI SYSTEM_MSI service group must not support the P2A doorbell system MSI.

  3. The message_id parameter passed to the sbi_mpxy_send_message_with_response() and sbi_mpxy_send_message_without_response() must represent the SERVICE_ID of an RPMI service belonging to the RPMI service group bound to the SBI MPXY channel.

  4. The format of the message data passed via the SBI MPXY shared memory to the sbi_mpxy_send_message_with_response() and sbi_mpxy_send_message_without_response() must match the request data format of the RPMI service represented by the message_id parameter.

  5. The format of the response message data returned in the SBI MPXY shared memory by the sbi_mpxy_send_message_with_response() must match the response data format of the RPMI service represented by the message_id parameter.

  6. The format of the protocol-specific data returned in the SBI MPXY shared memory by the sbi_mpxy_get_notification_events() must match the RPMI notifications message data format.

  7. The SBI MPXY channel must support message protocol attributes listed in the Table 1 below.

Table 1. RPMI Message Protocol Attributes of an SBI MPXY Channel
Attribute Name Attribute ID Access Description

SERVICEGROUP_ID

0x80000000

RO

RPMI service group ID.

SERVICEGROUP_VERSION

0x80000001

RO

RPMI service group version.

IMPLEMENTATION_ID

0x80000002

RO

RPMI implementation ID.

IMPLEMENTATION_VERSION

0x80000003

RO

RPMI implementation version.